AAHSTO’s HSM Part C uses SPFs to predict average crash frequency of three-leg and four-leg signalized and TWSC intersections. The HSM uses CMFs in Part C to compute the change in expected average crash frequency. CMFs less than one indicate a decrease in crash rates. HSM Part D includes additional CMF at stop-controlled, signalized, and roundabout intersections but is focused on conventional four-leg and three leg intersection types. CMFs cover the following intersection applications:

The HSM also provides CMFs related to geometric design changes, such as adding left-turn lanes to approaches on TWSC, AWSC, and signalized intersections. CMFs are not provided but crash trends are provided in the HSM for multimodal design changes, such as providing bicycle lanes, raised crosswalks, raised bicycle crossings, marked crosswalks, and refuge islands. Regarding alternative intersections, the HSM covers CMFs associated with replacing direct left-turns with right-turn/U-turn maneuvers at unsignalized intersections.